The heart is the center of the human circulatory system that pumps blood through our body. It is a muscle that pumps the blood only in one direction. In order for the heart to effectively maintain this unidirectional flow of blood, it must have properly functioning valves that prevent back flow through its system, or regurgitation. The heart is divided into four chambers: right and left atrium, and right and left ventricles. The four chambers are connected to the aorta, inferior and superior vena cava, pulmonary artery, and pulmonary veins.
The mitral valve (MV) separates left atrium from left ventricle while the tricuspid valve (TV) separates right atrium from the right ventricle. The aortic valve (AV) is located between the left ventricle and the aorta while the pulmonary valve (PV) is located between the right ventricle and the pulmonary artery.
Generally, valves should open and close completely with every heart beat or contraction. Incomplete opening or closing of the valves causes improper flow of blood. Valvular diseases are divided into two categories, regurgitation and stenosis. Regurgitation is a failure of a valve to close completely and stenosis is a failure of a valve to open completely.
Mitral valve regurgitation (MVR) is a common cardiac valve disorder that is caused by incomplete closure of the mitral valve (MV). The MV is located between the left atrium and the left ventricle. Over time, MVR places a burden on the heart and worsens its ability to pump blood properly. Such stress on the heart will ultimately lead to heart failure.
Traditional treatment for worsening MVR requires open heart surgery with sternotomy or thoracotomy with cardiac arrest and cardio-pulmonary bypass. Once the chest is open and access to heart is gained, the MV is either repaired or replaced using an artificial valve. Although very effective, this open-heart procedure is a high risk surgery accompanied by substantial morbidity and prolonged convalescence. Mortality due to surgery itself can be as high as 5%. As a result, the procedure often is not offered to patients who are insufficiently symptomatic to justify the surgical risk and morbidity, or to patients with substantial co-morbidity. It is reserved only for those with severe symptomatic MVR. This high morbidity rate of open heart surgery has motivated further research into developing a safer and less risky alternative to repair MV. Much of the research involves use of cardiac catheterization. Recently, the inventor of the present invention presented a thesis regarding “mitral valve cerclage coronary sinus annuloplasty (MVA” showing outstanding results of MVR treatment through applying circular pressure around the mitral annulus (MA). This thesis has been filed through PCT as an international patent application (PCT application number PCT/US2007/023836) and has been published (International publication number WO2008/060553).
The aforementioned thesis and published patent application disclosed the mitral cerclage coronary annuloplasty (MVA) procedure. Briefly explained, a catheter is placed in coronary sinus after accessing the right atrium through the jugular vein, and then a cerclage suture is passed through the proximal septal vein. This cerclage suture can easily pass through right ventricular outflow tract (RVOT), and this inventor defines this technique as “simple mitral cerclage annuloplasty”. Then, the cerclage suture can be easily pulled into the right atrium thus placing the cerclage suture circumferentially around the mitral annulus. Once positioned, tension is applied to the cerclage suture, thereby tightening the mitral valve. This brings together the two lobes of the MV so that they are approximated and reduce the size of its incomplete closure. This procedure can theoretically obtain very similar results to those that conventional surgeries can obtain by directly tightening the mitral annulus, and shows an immediate reduction of MVR.
However, the cerclage suture passes through the tricuspid valve and the heart, so it may reduce the function of the valve or may damage the valve and other parts. The inventor has developed a tissue protection device for the coronary sinus and the tricuspid valve and has filed a patent application as a technology for protecting tissues in a body (heart) and it has been registered (Korean Patent No. 10-1116867, registered on Feb. 8, 2012).